Submarine sound receiver



IVI. IVIASON.

SUBIVIARINE SOUND RECEIVER.

APPLICATloN FILED1uNE25,1919.

Patented Apr. 25

lulu /uMm INVENTOR.

PATENT OFFICE.

MAX MASON, F NEW LONDON, CONNECTICUT.

SUBMARINE SOUND RECEIVER.

Specification of Letters Patent.

Patented Apr. 25, 1922.

Application led June 25, 1919.. Serial No. 306,6844.

To all'wkom t may concern Be it known that I, MAX- MAsoN, a citizen ofthe "United States, residing at New London,in the county of New Londonand State `of Connecticut, have invented new and useful Improvements inSubmarine Sound Re` c ei'vers, of which the following is a' specication.

The present invention relates to sound receivers and mo're particularly`toso-called acoustiealsound receivers of the diaphragm type. The objectof the invention is to provide' asensitive substantially non resonantsound receiving diaphragm. To accomplish this result I employ asubstantially nonresonant, preferably thin diaphragm, which is supportedat a plurality of points distributed over-.its area in such a manner asto render it substantially non-resonant and substantially equallyresponsive overA a wide range of sound frequency.

' While the diaphragm sound receiver may be used for many purposes, suchfor eX- ample as a diaphragm for. a telephone microphone, it isparticularly applicable for submarine sound reception and I haveillustrated the invention as` embodied in areceiver for submarine work.For submarine sound detection and particularly for a multiunit submarinesound receiving device, it is essential thatthe in ividual sound`receiv- 'ers be substantially non-resonant, otherwise they willindividually vibrate at their own frequencies and out of phase, so thatexact superposition `in regard to phase of the sounds received from the'separate diaphragms will not occur at the collecting point and accuratefocusing will be impossible.

In the drawings which illustrate the preferred embodiment of myinvention Fig. 1 is an elevation of the receiver, Fig. 2 is an elevationof the backing plate, Fig. 3 is an elevation of one of the larger of thetwo wire guaze sheets, Fig. 4 is an elevation of one of the smaller ofthe gauze sheets, Fig. 5 is a section through the receiver along theline V-V of Fig. 1, Fig. 6 is a` section through the receiver along theline VIVI of Fig. 1, and Fig. 7 is a section through a receiverillustrating a modification.

Referring to the illustrated embodiment of the invention, the receivercomprises a comparatively heavy metal backing late 1 through whichpasses a pipe 2 which3 an f path or column from the receiver to der thesound waves.

forms the sound detecting instrument. A thin da phragm 3 is placedV infron-t of the backing plate l leaving an air chamber between it and thebacking plate. The function of the thin diaphragm 3 is to form ayielding wall orseparation-between the water in which the receiver isimmersed and the air in the chamber 4. A thin sheet of practically any,waterproof material may be used for this diaphragm. 'The diaphragm maybe made of thin sheet metal such .as aluminum, copper, brass, or thelike, or may be made of bakelite, rubber, etc. When the diaphragm 3ismade of metal it may be conveniently secured to the backing plate D bybeing spun over the edge and soldered, as shown in the drawings. In theair chamber 4 is placed a backing for the diaphragmwhich will supportthe diaphragm at a plurality of points against the hydrostatic pressureof Water in which it is submerged.

I have found that ordinary copper wire gauze is a suitable backingmaterial .for the diaphragm. It furnishesa large number of irregularlydistributed supporting points for the diaphragm. The supporting pointsthus furnished are not rigid but are yielding in various degrees andprovide a plurality of restoring forces of different intensities for thediaphragm as it vibrates un- This fact combined with the viscosity andradiation damping which is effective `on the diaphragm, produces aninstrumentl which is sensitive over a Wide range of frequencies andsufficiently non-resonant for use in multiple units. The viscositydamping is due to the. viscous re action of the air in the thin cavity4, the effect being a frictional resistance to the motion of thediaphragm. The radiation damping is due to the energy sent up theacoustical tube 2 as well as the energy sent lback into the water by themotion of the diaphragm 3.

The wire gauze backing is preferablyI made in two pieces as illustratedin the drawing, a large piece 6, which extends over 'the entire innerface of the'diaphragm, and

a smaller. piece 7 which is placed under the middle of the diaphragmover the mouth ofl the air tube 2.

While I prefer to use wire gauze Vor similar material which furnishes alarge number of irregularly distributed and irregularly yieldingsupporting Apoints for the diaphragm, a plurality of point supports maybe otherwise provided. For example, a plurality of diaphragm supportingpoints may be `formed integral with the backing plate l as shown inthemodiication illustrated in Fig. 7. f

In order to break up any resonant effect of the diaphragm 3 vibrating asa Whole, I prefer to cut the diaphragm in from its edges at a pluralityof places as indicated by vreference numerals 8 in Fig. 1. The sheet ofwire gauze G is similarly cut away as indicated at reference numerals 9on Fig. 3, and the edges of the piece of wire gauze 7 are notched asindicated by reference numerals l0 on Fig. 4, to register with the cutaway portions 8 of the diaphragm.

In assembling the receiver the piece of wire gauze 6 is placed on thebacking plate l, then the sheet of wire gauze 7 placed over it, and overthis is placed the diaphragm 3 and the edges of the diaphragm are turnedover the metal plate l. The pieces of wire gauze 6 and 7 are located sothat their cut away portions 9 and l0 register with the cut awayportions 8 on diaphragm 3. After the parts are assembled as abovedescribed, the edges of the cut away portions 8 of the diaphragm arevsoldered or otherwise fastened in a water tight manner through the slotsin the wire gauze to the face of the backing plate 1. This mode ofattaching the diaphragm 3 breaks up the diaphragm into a comparativelylarge number 'of smaller diaphragm areas, preventing the diaphragmvibrating as a whole. Vhile this breaking up of the diaphragm area isnot essential it has proved of advantage. The diaphragm being of a thiniexible material assumes the shape of the backing against which it ispressed under hydrostatic pressure, taking the form shown in Fig. 5, themiddle of the diaphragm being bulged outwardly over the double thicknessof wire gauze. This double thickness of Wire gauze is applied at thecenter to give a greater cross-sectional area to the air passageconnecting the tube 2 with the receiving cavity 4.

While I have specifically illustrated and described the preferredembodiment of my invention, it is to be understood that the invention isnot limited to its illust-rated embodiment but may be otherwise embodiedwithin the scope of the 4following claims:

I claim:

l. A sound receiver comprising a substantially nonresonant diaphragmdivided into a plurality of sectors and adapted to cooperate with asimilarly divided wire gauze backing, said wire gauze giving a pluralityof non-rigid supporting points adapted to withstand hydrostaticpressure, substann tially as described.

2. A sound receiver comprising a substantially non-resonant diaphragmand a backing comprising a plurality of non-rigid supporting pointstherefor exerting unequal restoring forces on the diaphragm,substantially as described.

A sound receiver comprising a diaphragm arranged to be subjected tohydrostatic pressure and a backing for the dia phragm comprising a sheetof wire gauze contacting with it at a plurality of points distributedover its area, substantially as described.

4. Ahsound receiver comprising a backing plate, a non-resonant diaphragmover the platdivided into a plurality of sectors, and a plurality ofsupporting points separating and holding the diaphragm away from thebacking plate, substantially as described.

MAX MASON.

